He also served in the royal army as a Captain and assisted his father in the defeat of the pretender Perkin Warbeck at the siege of Exeter in 1497, which secured the Tudor succession at last.
King Henry VII discovered that he had joined in the conspiracy to crown Edmund de la Pole, 3rd Duke of Suffolk (d. 1513), the last Yorkist claimant.
Released from prison by Henry VIII (1509–1547), Courtenay received a pardon and the restoration of his rights and privileges as a sword bearer at the coronation on 24 June 1509.
In October 1495 he married Catherine of York, the sixth daughter of King Edward IV and Elizabeth Woodville and sister to the then-queen.
The effigy appears to contain errors—records show that Margaret was still alive and serving Princess Mary Tudor, daughter of Henry VIII, on 2 July 1520.